Police are undertaking a specific line of enquiry after a structure fire at a unit complex in Kingston overnight was deemed suspicious.

Police and emergency services were called to an address in Redwood Road, Kingston about 5.50pm yesterday with Tasmania Fire Service extinguishing the fire.

A 43-year-old man was rescued from the unit and taken to the Royal Hobart Hospital in a serious condition.

The damage to the unit was considered moderate and investigations are continuing.

No other occupants of the unit complex were injured as a result of the fire.

Anyone with information should contact Kingston Police on 131 444 or Crime Stoppers via www.crimestopperstas.com.au. You can do so anonymously.